This invention relates to a motor vehicle glazing provided for bonding with the window frame of a motor vehicle body. More particularly, it relates to a profile bead placed along the glazing edge that forms an intermediate body between the glazing and an assembly adhesive that secures the glazing in the window frame and to a wire or a flexible tear-away cord with high tensile strength placed inside or immediately next to the profile bead to shear the profile bead when removing the glazing.
In a known installation method (U.S. Pat. No. 4,876,132), a profile bead is deposited by extrusion of an adhesive on the edge of the glazing and a flexible tear-away cord is placed either in the core of the profile bead or in its immediate vicinity. After setting, the profile bead serves as an intermediate body or intermediate layer between the glazing and the assembly adhesive. In this known process, to remove the glazing from the vehicle, the flexible cord must shear the entire width of the profile bead to sever the bond between the glazing and the window frame. Since the adhesives used for the profile bead are materials that harden in the set condition and exhibit a comparatively high shear strength, comparatively high tensile stresses are required to shear the profile bead over the entire width of said bead. Therefore, there is a risk that in the process of shearing the profile bead the breaking load of the tear-away cord will be exceeded, and the cord will break, leaving the glazing secured in place in the window frame.
While the tensile stresses required to shear the profile bead decrease as the width of the profile bead decreases, a reduction in the width of the profile bead cannot be used to avoid the risk of a broken tear-away cord. For proper installation of the glazing a certain minimum cross section is required for the assembly adhesive that secures the profile bead and hence the glazing to the window frame. A profile bead that is too narrow would result in the assembly adhesive flowing out laterally over the profile bead when the glazing is inserted and result in the enlargement of the cross section to be sheared through.
To reduce the forces necessary to shear the profile bead, it has already been proposed (U.S. Pat. No. 4,876,132) to place multiple tear-away cords inside the profile bead or immediately next to the bead. To remove the glazing with such an arrangement, each of the cords cuts through only a part of the cross section of the profile bead thereby reducing the tensile stresses on the cords. However, embedding or placing multiple cords is an additional expense.